TO be fair, despite the US having some large emptier states, the US has nodes of very high urban density - most notably the Northeast corridor. From Boston to W

TO be fair, despite the US having some large emptier states, the US has nodes of very high urban density - most notably the Northeast corridor. From Boston to Washington there's around 50 million people, with - depending how you define it - a density of around 390/sqkm, three times that of France's 120/sqkm. Of course not representative, but you can definitely see the influence of the automobile in how these cities have grown. Compare to say, Moscow - another major urban city in a fairly sparse city - New York City has only added a few km of subway lines in the past 20 years compared to 150+km.